Oil sands, which may also be known in the art as “tar sands” or “bituminous sands,” are a type of petroleum deposit. Oil sands comprise mineral particles (e.g., clays and/or sand) along with connate water and bitumen. Bitumen is a mixture of hydrocarbons, and, once recovered from the oil sands, may be refined for further use, as with other petroleum product refining. Economically recovering bitumen from oil sands, however, often poses challenges.
Flotation is a common technique used to recover bitumen from oil sand ore. In flotation, oil sand ore, water, and possible other additives are fed to a flotation cell in which the materials are agitated and air is bubbled through. The vigorous mechanical agitation and the aeration from the bubbled air, along with the influence of possible chemical additives and temperature, disrupts the granules of the oil sand ore, causing the bitumen to separate from the mineral particles (e.g., clays and/or sand particles) of the oil sand ore. Once separated, the bitumen may come into contact with the air bubbles, which urge the bitumen droplets upward to form a bitumen-rich froth. The froth “floats” or rises to form a phase that is separable from a “middlings” layer, comprising residual bitumen and suspended mineral particles, and a bottom layer, comprising water and mineral “fines” that have settled due to gravity. Obtaining a good yield of bitumen product from the oil sands is desired to minimize costs and wastes of the flotation process.
Efforts have been made to increase the yield of bitumen recovery by adding one or more flocculants to the slurry in the flotation cell. Flocculants are generally configured to encourage particles dispersed in the slurry to form larger-sized clusters, generally known in the art as “flocs” or “flakes,” that may either rise to the froth layer or sink to the bottom layer. Formulating flocculants and designing bitumen recovery systems that achieve maximum yield of bitumen recovery from oil sands continues to present challenges.